/**
 * Copyright 2009 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package org.waveprotocol.wave.model.document.operation.algorithm;

/**
 * An pair of strings representing an update of a string value.
 */
final class ValueUpdate {

  final String oldValue;
  final String newValue;

  ValueUpdate(String oldValue, String newValue) {
    this.oldValue = oldValue;
    this.newValue = newValue;
  }

  @Override
  public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((newValue == null) ? 0 : newValue.hashCode());
    result = prime * result + ((oldValue == null) ? 0 : oldValue.hashCode());
    return result;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj) return true;
    if (obj == null) return false;
    if (!(obj instanceof ValueUpdate)) return false;
    ValueUpdate other = (ValueUpdate) obj;
    if (newValue == null) {
      if (other.newValue != null) return false;
    } else if (!newValue.equals(other.newValue)) return false;
    if (oldValue == null) {
      if (other.oldValue != null) return false;
    } else if (!oldValue.equals(other.oldValue)) return false;
    return true;
  }

}
